Landfill sites can be generally defined as areas where waste materials are disposed of over years. In general, land filling operations imply daily covers of granular materials and final covers constructed with impermeable materials such as clay or geo membranes. Municipal solid wastes or the like often include wastes of various natures having a relatively high fraction of organic matter. The organic fraction slowly decays over time, generating what is referred to as the landfill gas. This landfill gas includes mostly methane (CH4) and carbon dioxide (CO2). It also includes other gases in minor proportions. The methane gas is a valuable source of energy but is also a greenhouse gas if released in the atmosphere. Landfill gas capture offers significant environmental and economic benefits when used in a waste-to-energy project. However, landfill gas capture can be very challenging when considering the difficulties in handling the collected materials associated with the landfill gas capture operation. These collected materials form what is referred to hereafter as the raw multi-phase stream. The raw multi-phase stream is a mixture of gases, liquids and solids varying in proportions over time and even from one location to another in the same landfill site. In a landfill site, a raw multi-phase stream can be captured from one landfill gas collector or from a network of landfill gas collectors.
Generally, the raw multi-phase stream tends to plug the landfill gas collector because of the accumulation of solids and liquids. It can also plug the landfill gas collector under cold weather conditions. The raw multi-phase stream thus often requires high maintenance and operation costs. If not managed correctly, it can compromise the overall financial viability of a waste-to-energy project by impacting the quantity and the quality of the collected landfill gas. Still, the technical complexities associated with the handling of a raw multi-phase stream and the extent of the financial investments make smaller landfill sites less attractive for waste-to-energy projects or other greenhouse gas reduction projects.
Accordingly, there is still room for many improvements in this area of technology.